Tevatron experiments see possible signs of the Higgs boson in favored region

03/07/12

Experiments at the Tevatron collider have seen possible hints of the Higgs boson. Image: Fermilab

The intrigue continues to build in the pursuit of the Higgs boson.

Physicists from both experiments at Fermilab’s Tevatron collider near Chicago announced today that they may have spotted hints of the long-sought particle. Those hints are compatible with results that scientists at the Large Hadron Collider near Geneva released in December 2011.

Tevatron physicists told attendees of the Rencontres de Moriond conference this morning that they had found excesses in their data suggestive of a Higgs with a mass between 115-135 gigaelectronvolts. A few months ago, LHC physicists announced similar bumps indicating a Higgs with a mass of between 124-126 GeV.

“The end game is approaching in the hunt for the Higgs boson," said Jim Siegrist, DOE Associate Director of Science for High Energy Physics. “This is an important milestone for the Tevatron experiments and demonstrates the continuing importance of independent measurements in the quest to understand the building blocks of nature.”

Neither the Tevatron nor the LHC Higgs search results reach the level of statistical significance required to declare a discovery, but the growing body of evidence has captivated particle physics enthusiasts.

The Tevatron results come from the complete dataset of America’s largest particle accelerator, which finished its last run in September 2011.

The ATLAS and CMS experiments also gave Higgs hunters a confidence boost at today’s conference. After adding new searches and making refinements to their data, both of the LHC experiments continued to see possible hints of the particle in the same range, though the signal in one of the searches by the ATLAS experiment had weakened slightly.

LHC experiments have collected no new data since last year’s Higgs announcement; the accelerator has been shut down for its annual technical stop since December. But they have continued to cultivate results using the data they have. Both experiments made progress by conducting new types of searches.

Massive particles decay quickly into lighter ones after being produced in collisions in particle accelerators like the LHC and the Tevatron. The Higgs boson has several options of where to go (or whom to be) when it decays, but it is more inclined to break down into some particles than others.

Scientists on the ATLAS experiment focused on the most-likely decay scenarios in December. Today, they presented results examining several new decay channels, about doubling the amount of data they have sifted through in search of the Higgs. This may sound like a giant leap forward, but the likely rarity of Higgs decays in the additional channels muted their contributions to the investigation.

The CMS experiment dramatically improved their search in one channel in particular, Higgs bosons decaying into pairs of gamma rays. The new results nudged a bump in their data a bit closer to similar ATLAS results. “We’re not talking about kilometers, but it’s still interesting,” said ATLAS spokesperson Fabiola Gianotti.

It’s still too soon, though, to say whether scientists have pinpointed the possible location of the Higgs. The experiments see bumps at a few other spots in the low-mass range as well. “To me, it’s still very much an open question,” said CMS spokesperson Joe Incandela. “We’ve got to get to new data quickly.”

The four Higgs-hunting experiments – CDF, DZero, ATLAS and CMS – will continue to work independently and together in their drive to investigate the entire possible mass range for the Higgs boson. If they can keep up the pace, there shouldn’t be much road left between them and what they’re looking for.